1. Field of the Invention
The present invention relates to papermaking fabrics. More particularly, it relates to utilizing hook and loop mesh fastener material to secure modular panels as a base fabric for a press felt or to seam a papermaking fabric.
2. Description of the Prior Art
Papermaking fabrics are used to form, transport, dewater and dry paper on a papermaking machine. Papermaking press felts are designed to transport an aqueous web of paper through the press rollers of a papermaking machine and to assist in the de-watering of the paper web. Commonly, a papermaking wet press felt is constructed from a woven base fabric having batt material needled to one or both sides.
The felts may be woven as endless felts, however, the use of a seam to join the ends of a flat felt into an endless felt is often desirable as it allows for ease of installation of the felt onto the papermaking machine. The seam may be of the pin type which utilizes a joining wire or pintle to secure opposing series of seaming loops projecting from the fabric's ends together. The insertion of a pintle is generally tedious and time consuming and can damage the seaming loops. Additionally, the high speed and conditions of operation often result in extreme conditions of wear at the seam. Many attempts to strengthen the seam have resulted in seams which are not uniform with the rest of the felt whereby undesirable markings and/or irregularities in the paper product result. As such, it is desirable to provide a seam which can be joined more efficiently while maintaining the characteristics and strength of the fabric.
During the papermaking process, papermaking fabrics are sometimes subjected to accidental perforation. A perforated fabric causes defects in the paper made therewith and must be replaced or repaired. A typical fabric may be 90 feet in length and 20 feet wide and cost upwards of $30,000 or more. Accordingly, the ability to provide a repairable fabric is desirable.
In the case of large tears or holes, a papermaking fabric cannot easily be repaired. In areas where longitudinal machine direction yarns are interrupted over a substantial width, a fabric forms a wave or ridge which has a detrimental effect on paper quality and safe operation. In cases of minor damage areas, i.e. having damage less than 20 millimeters, which tend to occur more a frequently, it is generally practical to continue using the papermaking fabric, at least for some time, on non-mark critical paper grades.
Prior art methods of fixing damaged fabrics include manual restitching over the damaged area using substitute yarns. However, this method is very time consuming and difficult to perform and can only be done by experienced and trained personnel. In addition, the mending method takes a long time and shut down costs of the machine are very high.
An alternate method for repairing damaged fabrics is patching with a woven patch. However, selecting a proper patch is difficult since the proper type of patch and adhesive must be chosen and the patch cannot be too thin or too thick so as to form an uneven paper surface. In addition, this method of repair cannot be used with press fabrics.
Another prior art attempt for patching damaged areas includes ultrasonic welding of a patch to the damaged area. However, this can be a problem with synthetic fibers, i.e. nylon and polyester, in that the heat from the weld can damage the materials. In addition, the welding requires skilled and trained personnel to perform the operation and furthermore, cannot be utilized with press fabrics.
Thus it is desirable to provide a laminated multi-layer base fabric for a press felt which combines the ease of installation of a flat woven fabric while maintaining the fabric characteristics of an endless woven fabric.